I had following setup complete and i was seeing the .trace files successfully created after hitting requests to my resource.
init(Config) ->
%% enable tracing the decision core for debugging
{{trace, "traces"}, Config}.

escript is packaged as part of the erlang otp and essentially executes uncompiled erlang code. Rebar delegates alot of work to it. Recently, I was getting the following error when trying to run the webmachine project files from the excellent book, ‘7 webservers in 7 weeks‘.

The model and ddl can be verified by hitting cb_admin and going to the model section

REST Contract/Controller

As mentioned we are going to have do CRUD actions on the book entity by have four services exposed. The logic is contained in a controller class, relevant extracts are explained below and full file is available on github